The power to counter physical fatigue and increase alertness is part of the reason caffeine ranks as the world's most popular mood altering drug. It is found not only in sodas, energy drinks, coffee, and tea, but also in diet pills, pain relievers (like aspirin), and chocolate bars. Many societies around the world have also created entire rituals around the use of caffeine: afternoon tea in the U.K., the café culture of France, tea ceremony In Japan, and the morning cup of coffee or tea that in many cultures marks the start of the day.